'Colossal' American oil boom could spoil OPEC's plans

The oil cartel and key ally Russia have spent more than a year trying to drain the world of excess supply. But the International Energy Agency warned Tuesday that a "colossal" oil boom in the United States could ruin their efforts.

The Paris-based agency said that a massive increase in output means the U.S. will soon be producing more oil than Saudi Arabia. It could soon challenge Russia for the global crown.

The manic American pumping, which the IEA estimates will average 10.4 million barrels a day this year, could cause a glut to return to global markets.

"U.S. producers are enjoying a second wave of growth so extraordinary that in 2018 their increase in liquids production could equal global demand growth," the IEA said in its latest monthly report. "This is a sobering thought for other producers."

The IEA said the surge, which is powered by shale, is "reminiscent" of 2014, when booming production in the U.S. prompted OPEC to flood the global market with oil in an attempt to protect its market share.

The strategy led to a price collapse that sent crude to a low of $27 per barrel in 2016 from well over $100.

Plunging prices forced some higher-cost U.S. producers to close up shop. But many emerged leaner and stronger than before.

OPEC and other major producers including Russia agreed to slash their output in late 2016 in order to reduce the glut and help boost prices. The agreement has been extended until the end of 2018.

But there are signs that the strategy may be losing its effectiveness.